Torpedo



Feb. 6, 1940.

R. A. HUNTER 2,189,398

TORPEDO Filed Sept. 28, 1937 2 Sheets-Sheet 1 FIG; IL

WITNESS S.- INVENTOR- M W I Rex fi ifilniier,

gM QML By C ATTORNEYS.

R. A. HUNTER Feb. 6, 1940.

TORPEDO Filed Sept. 28. 19s? 2 Sheets-Sheet 2 INVENTOR: Rex 5C ifu W 1 TN ESSES ATTORNEYS.

Patented Feb. 6; 1940 warren sra'rss PATENT QFFifiE 2 Claims.

My invention relates to torpedoes, and especially torpedoes intended to be exploded by pressure rather than by mere shock. or impact. Such torpedoes are useful for signalling on railways, and I have hereinafter explained my invention with particular reference to railway torpedoes.

Railway torpedoes are intended to be secured on a railroad track to explode under a train or locomotive passing over them, so as to give warning of conditions of danger ahead. The torpodoes heretofore in use have been subject to several drawbacks, amongst which I may mention a cerw tain instability or risk of premature explosion by minor shocks, and a tendency to draw and absorb moisture from the atmosphere, not only when used in wet weather, but even when in storage. The instability and risk of premature explosion extend to the pyrotechnic or explosive compositions used in such torpedoes: e. g., these compositions have proved very dangerous in the factory, where explosions resultingin severe injury or death of workers have often occurred.

I aim to produce torpedoes that are free of such drawbacks: i. e., immune to any ordinary shock or impact; not absorbent of moisture, and reliable in their action when kept a long time before use; and free from danger of accidental explosion during' manufacture. The invention involves the process of manufacture, as well as, the construction of the torpedoes, and the explosive' composition employed in them. Various other features and advantages of the invention will appear from the following description of species or forms of embodiment, and from the drawings. All features and combinations shown or described are, indeed, of my invention, so far as novel over the prior art. In the drawings, I

Figs. I, II, and III are top and bottom plan and side views of a form of torpedo conveniently embodying my invention.

Fig. IV is a top plan View of the body of the torpedo casing.

Fig. V shows a vertical mid-section through a torpedo, taken as indicated by the line and arrows VV in Fig. I.

Fig. V1 is a similar view, the section being taken at right angles to Fig. V.

Fig. VII is a perspective view of a torpedo applied. to a rail head, as in practical use.

As shown in Figs. I-VI, the torpedo comprises a lar) pan-like body or cup I2 (Fig. IV) with a fiat closure I3 securedthereto, as by folding or crimping over its edge I i on a top flange l5 of the body. For securing the torpedo on the head of a track rail, the casing I is preferably provided with a flexible (metal) strap l6, shown as interposed between the body i2 and its closure l3. This strap H may be secured by ears I! on the body flange 1 15, which are shown folded over on the closure l3. When charged with explosive and closed as described, the casing lll may be sealed watertight by coating it externally with shellac or other waterproof substance. The bottom of the casing body 12 is internally coated with grains of abrasive sand or the like 29, to, assist in setting off the explosive when a train passes over the torpedo. As shown, one side of the casing [0 (that formed by the closure l3, in this instance) is externally coated with grains of abrasive sand or the like 22, to prevent slippage of the torpedo on a rail.

The cup-like casing body I2 is preferably made of lead alloyed with a minor proportion of antimony,just enough to facilitate drawing and shaping the sheet lead in suitable dies. The thickness of this sheet lead may be about .008 inch or more. The inner body surface is coated with adhesive such as glue or shellac (say 2 /2 cut orange shellac such as hereinafter described),

and the fine sand is sifted on,--the surplus that does not stick to the wet adhesive being shaken off. The closure I3 is preferably of sheet aluminum, say about .008 inch thick. The strap I6 may be a strip of sheet lead .040 inch thick, 1% inch wide, and 7% inches long. In use, the torpedo is preferably secured to rail with its body l2 uppermost, by bending the ends of the strap l6 under the rail head, as shown in Fig. VII. i

For the explosive charge or pellet 9, I employ a composition comprising fuel and oxidizing agents as its principal active ingredients, and preferably including material such as will afford a conspicuous volume of smoke and an increased volume of sound, without any tendency to injure either the rail or the (locomotive) wheel or tire passing over the torpedo. Oxidizable metals used as fuels also afford a dense smoke (generally white) owing to the fine solid particles of refractory oxide produced by their suddenoxidation in the ex plosion. Ofsuch metals, aluminum is at present preferred, since it is decidedly the cheapesh-andv is available commercially in 'a finely divided state,particularly the dus of commerce. I

For the main portion of the fuel, or reducing agent, however, I prefer more readily ignitable and less expensive material, and particularly sulphides of readily oxidizable metals, such as antimony sulphide. Sulphur in a free state is,

however, to be avoided; for I have found that so-called aluminum parts alcohol is very suitable.

mula for the more active ingredients is as follows, the proportions being by weight:

Parts Potassium chlorate 16 Antimony sulphide 1 Aluminum metal dust 1 All of these ingredients should be in a finely powdered state when mixed'together.

It will beunderstood, of course, that in prac tice the explosive charge 5) may contain inert or subsidiary ingredients, which are often used in torpedoes, such as sand 'or powdered glass, or substances for coloring the explosive flash, or binders; and that in stating in my claims that the charge consists of certain substances, 1 refer to the active ingredients that make it. an explosive charge, and do not mean to exclude the presence of inert or subsidiary ingredients, whether as diluents, or for subordinate useful purposes. For instance, with the more active ingredients (fuel and oxidizer) above indicated, I prefer to associate a water resistant binder such as a varnish, like shellac, dissolved in a solvent such as alcohol: e. g., commercial grain or wood alcohol, or denatured alcohol. Orange shellac cut with denatured alcohol in the proportion by weight of 2 parts shellac to 6 ,4; With the main fuel and oxidizing ingredients in the above formula I use enough of this 2 cut shellac to make a paste or slurry that can be readily moulded as hereinafter described. I have found, however, that danger of explosion can'be obviated by a special mode of mixing the ingredients together, v1z.:

To the oxidizer (potassium chlorate) the binder (shellac) is added as a dry powder, and they are thoroughly mixed together. This may preferably be done dry, without any solvent for the binder being present; if so, the solvent (alcohol) for the binder is then added and thoroughly mixed in. After this, I add the fuel or reducing ingredient (s) ,already mixed together, if a combination of fuels (as antimony sulphide and aluminum dust) is use'd,and thoroughly mix the fuel in with the slurry already formed by the other ingredients.

While the final paste or slurry might be poured and molded directly in the casing body l2 after lining the same with the (Cellophane) wrapping sheet I l, I generally preferto form the explosive pellet 9 by pouring the final paste mixture suitable charge.

into a suitable metal die or mold, not shown. About 7 grams of the slurry or paste forms a This may be placed in a hot room or other drying atmosphere for some 48 hours, to dryout all moisture, as Well asto evaporate off all the alcohol. The solid dried pellet 9 may then be removed from the mold,'

wrapped up in the Cellophane ii, and placed in the body l2, which has previously been coated with the sand 20 as already mentioned. The abrasive grains 20 may be a fine natural quartz tered both transversely and longitudinally relative to the casing; and the closure sheet I3 is placed over the casing and its edges I4 are crimped around the casing flange l5. The edges of the casing ears i! (Fig. IV) are turned up and inward and folded down as shown in Figs. I and III,-in other Words, crimped around the edges of the strap Hi and the closure projections l8. Then the torpedo is coated and sealed air-tight and waterproofed with shellac, preferably using a 2 cut solution such as already described. This may be done by immersing the whole torpedo in the shellac and allowing it to dry. While the shellac coating is still wet, grains of abrasive sand 22 (similar to the sand 20 used inside the casing) may be sifted org-the surplus being taken 01f after the coating has dried.

The completed torpedo is thoroughly moisture proof, by reason of the shellac in the pellet 9, as well as by virtue of the shellac coating of'the casing. It is exceedingly safe to handle, to ship (by rail or truck), and to use. This is illustrated by the fact that in a drop test my torpedo requires a 45 lbs. weight dropped on it from a height oi 18 ft. to explode it; whereas the priorused railway torpedoes explode under a weight but 5 lbs. dropping only 2 ft. Likewise, tests have shown that when a box of my torpedoes packed for shipment is struck and penetrated by a rifle bullet, explosion or combustion of the torpedoes en masse does not ensue, even though the torpedoes actually penetrated by the bullet do burn completely. That my torpedoes do not detonate or explode en masse is a safety factor of great importance; for all other railway torpedoes on the market do explode en masse when a box is struck by a bullet,which in the case of large shipment in a railway car or a motor truck would result in a very serious wreck. Experience has shown that in manufacture there is no danger of explosion and resulting injury to Workmen,--the only hazard being that from The dried out material of the pellet 9 is a fire. solid cake that can be removed from the casing H, cut with a knife, filed with a file, and set afire by lighting it with a match,all without danger of explosion. In fact, it can only be exploded under great load, such as that of a locomotive passing over it, or a heavy weight dropping from a considerable height as in the test mentioned above.

Having thus described my invention, I claim:

1. A torpedo having as its charge an explosive mixture consisting of chlorate as oxidizer, antimony sulphide as fuel, and a minor proportion of aluminum as a smoke-producing auxiliary fuel, but free of free sulphur, and explosive under heavy pressure but not by heat orminor percussions and shocks.

2. A torpedo composition consisting of chlorate as oxidizer, antimony sulphide as fuel, and a minor proportion of aluminum as a smokeproducing auxiliary fuel, but free of free sulphur, together with a water-resistant varnish binder uniting the particles of the composition into a coherent mass, and explosive under heavy pressure but not by heat or minor percussions and shocks. v

REX A. HUNTER. 

